Identification Documents
Identification documents (hereafter “ID documents”) play a critical role in today's society. One example of an ID document is an identification card (“ID card”). ID documents are used on a daily basis—to prove identity, to verify age, to access a secure area, to evidence driving privileges, to cash a check, and so on. Airplane passengers are required to show an ID document during check in, security screening and prior to boarding their flight. In addition, because we live in an ever-evolving cashless society, ID documents are used to make payments, access an automated teller machine (ATM), debit an account, or make a payment, etc.
(For the purposes of this disclosure, ID documents are broadly defined herein, and include, e.g., credit cards, bank cards, phone cards, passports, driver's licenses, network access cards, employee badges, debit cards, security cards, visas, immigration documentation, national ID cards, citizenship cards, social security cards, security badges, certificates, identification cards or documents, voter registration cards, police ID cards, border crossing cards, legal instruments, security clearance badges and cards, gun permits, gift certificates or cards, membership cards or badges, etc., etc. Also, the terms “document,” “card,” “badge” and “documentation” are used interchangeably throughout this patent application.).
Many types of identification cards and documents, such as driving licenses, national or government identification cards, bank cards, credit cards, controlled access cards and smart cards, carry thereon certain items of information which relate to the identity of the bearer. Examples of such information include name, address, birth date, signature and photographic image; the cards or documents may in addition carry other variant data (i.e., data specific to a particular card or document, for example an employee number) and invariant data (i.e., data common to a large number of cards, for example the name of an employer). All of the cards described above will hereinafter be generically referred to as “ID documents”.
As those skilled in the art know, ID documents such as drivers licenses can contain information such as a photographic image, a bar code (which may contain information specific to the person whose image appears in the photographic image, and/or information that is the same from ID document to ID document), variable personal information, such as an address, signature, and/or birthdate, biometric information associated with the person whose image appears in the photographic image (e.g., a fingerprint), a magnetic stripe (which, for example, can be on the a side of the ID document that is opposite the side with the photographic image), and various security features, such as a security pattern (for example, a printed pattern comprising a tightly printed pattern of finely divided printed and unprinted areas in close proximity to each other, such as a fine-line printed security pattern as is used in the printing of banknote paper, stock certificates, and the like).
An exemplary ID document can comprise a core layer (which can be pre-printed), such as a light-colored, opaque material (e.g., TESLIN (available from PPG Industries) or polyvinyl chloride (PVC) material). The core is laminated with a transparent material, such as clear PVC to form a so-called “card blank”. Information, such as variable personal information (e.g., photographic information), is printed on the card blank using a method such as Dye Diffusion Thermal Transfer (“D2T2”) printing (described further below and also described in commonly assigned U.S. Pat. No. 6,066,594, which is incorporated herein by reference in its entirety.) The information can, for example, comprise an indicium or indicia, such as the invariant or nonvarying information common to a large number of identification documents, for example the name and logo of the organization issuing the documents. The information may be formed by any known process capable of forming the indicium on the specific core material used.
To protect the information that is printed, an additional layer of transparent overlaminate can be coupled to the card blank and printed information, as is known by those skilled in the art. Illustrative examples of usable materials for overlaminates include biaxially oriented polyester or other optically clear durable plastic film.
In the production of images useful in the field of identification documentation, it may be desirable to embody into a document (such as an ID card, drivers license, passport or the like) data or indicia representative of the document issuer (e.g., an official seal, or the name or mark of a company or educational institution) and data or indicia representative of the document bearer (e.g., a photographic likeness, name or address). Typically, a pattern, logo or other distinctive marking representative of the document issuer will serve as a means of verifying the authenticity, genuineness or valid issuance of the document. A photographic likeness or other data or indicia personal to the bearer will validate the right of access to certain facilities or the prior authorization to engage in commercial transactions and activities.
Identification documents, such as ID cards, having printed background security patterns, designs or logos and identification data personal to the card bearer have been known and are described, for example, in U.S. Pat. No. 3,758,970, issued Sep. 18, 1973 to M. Annenberg; in Great Britain Pat. No. 1,472,581, issued to G. A. O. Gesellschaft Fur Automation Und Organisation mbH, published Mar. 10, 1976; in International Patent Application PCT/GB82/00150, published Nov. 25, 1982 as Publication No. WO 82/04149; in U.S. Pat. No. 4,653,775, issued Mar. 31, 1987 to T. Raphael, et al.; in U.S. Pat. No. 4,738,949, issued Apr. 19, 1988 to G. S. Sethi, et al.; and in U.S. Pat. No. 5,261,987, issued Nov. 16, 1993 to J. W. Luening, et al. All of the aforementioned documents are hereby incorporated by reference.
Printing Information onto ID Documents
The advent of commercial apparatus (printers) for producing dye images by thermal transfer has made relatively commonplace the production of color prints from electronic data acquired by a video camera. In general, this is accomplished by the acquisition of digital image information (electronic signals) representative of the red, green and blue content of an original, using color filters or other known means. Devices such as digital cameras, optical sensors, and scanners also can provide digital image information. The digital image information is utilized to print an image onto a data carrier. For example, information can be printed using a printer having a plurality of small heating elements (e.g., pins) for imagewise heating of each of a series of donor sheets (respectively, carrying diffuseable cyan, magenta and yellow dye). The donor sheets are brought into contact with an image-receiving element (which can, for example, be a substrate) which has a layer for receiving the dyes transferred imagewise from the donor sheets. Thermal dye transfer methods as aforesaid are known and described, for example, in U.S. Pat. No. 4,621,271, issued Nov. 4, 1986 to S. Brownstein and U.S. Pat. No. 5,024,989, issued Jun. 18, 1991 to Y. H. Chiang, et al. Each of these patents is hereby incorporated by reference.
Dye diffusion thermal transfer printing (“D2T2”) and thermal transfer (also referred to as mass transfer printing) are two printing techniques that have been used to print information on identification cards. For example, D2T2 has been used to print images and pictures, and thermal transfer has been used to print text, bar codes, and single color graphics.
Dye diffusion is a thermal imaging technology that allows for the production of photographic quality images. In dye diffusion printing, one or more thermally transferable dyes (e.g., cyan, yellow, and magenta) are transferred from a donor, such as a donor dye sheet or a set of panels (or ribbons) that are coated with a dye (e.g., cyan, magenta, yellow, black, etc.) to a receiver sheet (which could, for example, be part of an ID document) by the localized application of heat or pressure, via a stylus or thermal printhead at a discrete point. When the dyes are transferred to the receiver, the dyes diffuse into the sheet (or ID card substrate), where the dyes will chemically be bound to the substrate or, if provided, to a receptor coating. Typically, printing with successive color panels across the document creates an image in or on the document's surface. Dye diffusion can result in a very high printing quality, especially because the energy applied to the thermal printhead can vary to vary the dye density in the image pixels formed on the receiver, to produce a continuous tone image. Dye diffusion can have an increased cost as compared to other methods, however, because of the special dyes needed and the cost of dye diffusion ribbons. Also, the quality of dye diffusion printed image may depend at least on an ability of a mechanical printer system to accurately spatially register a printing sequence, e.g., yellow, magenta, cyan, and black.
Another thermal imaging technology is thermal or mass transfer printing. With mass transfer printing, a material to be deposited on a receiver (such as carbon black (referred to by the symbol “K”)) is provided on a mass transfer donor medium. When localized heat is applied to the mass transfer donor medium, a portion (mass) of the material is physically transferred to the receiver, where it sits “on top of” the receiver. For example, mass transfer printing often is used to print text, bar codes, and monochrome images. Resin black mass transfer has been used to print grayscale pictures using a dithered gray scale, although the image can sometimes look coarser than an image produced using dye diffusion. However, mass transfer printing can sometimes be faster than dye diffusion, and faster printing can be desirable in some situations.
Printing of black (“K”) can be accomplished using either dye diffusion or mass transfer. For example, black monochrome “K” mass transfer ribbons include Kr (which designates a thermal transfer ribbon) and Kd (which designates dye diffusion).
The term “D2T2” is a combination of the following phrases “Dye Diffusion” (D2) and “Thermal Transfer” (T2); T2 is a mass transfer ribbon panel and performs in a similar fashion as any other mass transfer technology.
Both dye diffusion and thermal ink have been combined in a single ribbon (e.g., D2T2 ribbon), which is the well-known YMCK (Yellow-Magenta-Cyan-Black) ribbon (the letter “K” is used to designate the color black in the printing industry). Another panel containing a protectant (“P”) or laminate (typically a clear panel) also can be added to the YMCK ribbon).
Manufacture and Printing Environments
Commercial systems for issuing ID documents are of two main types, namely so-called “central” issue (CI), and so-called “on-the-spot” or “over-the-counter” (OTC) issue.
CI type ID documents are not immediately provided to the bearer, but are later issued to the bearer from a central location. For example, in one type of CI environment, a bearer reports to a document station where data is collected, the data are forwarded to a central location where the card is produced, and the card is forwarded to the bearer, often by mail. Another illustrative example of a CI assembling process occurs in a setting where a driver passes a driving test, but then receives her license in the mail from a CI facility a short time later. Still another illustrative example of a CI assembling process occurs in a setting where a driver renews her license by mail or over the Internet, then receives a drivers license card through the mail.
In contrast, a CI assembling process is more of a bulk process facility, where many cards are produced in a centralized facility, one after another. (For example, picture a setting where a driver passes a driving test, but then receives her license in the mail from a CI facility a short time later. The CI facility may process thousands of cards in a continuous manner.).
Centrally issued identification documents can be produced from digitally stored information and generally comprise an opaque core material (also referred to as “substrate”), such as paper or plastic, sandwiched between two layers of clear plastic laminate, such as polyester, to protect the aforementioned items of information from wear, exposure to the elements and tampering. The materials used in such CI identification documents can offer the ultimate in durability. In addition, centrally issued digital identification documents generally offer a higher level of security than OTC identification documents because they offer the ability to pre-print the core of the central issue document with security features such as “micro-printing”, ultra-violet security features, security indicia and other features currently unique to centrally issued identification documents.
In addition, a CI assembling process can be more of a bulk process facility, in which many cards are produced in a centralized facility, one after another. The CI facility may, for example, process thousands of cards in a continuous manner. Because the processing occurs in bulk, CI can have an increase in efficiency as compared to some OTC processes, especially those OTC processes that run intermittently. Thus, CI processes can sometimes have a lower cost per ID document, if a large volume of ID documents are manufactured.
In contrast to CI identification documents, OTC identification documents are issued immediately to a bearer who is present at a document-issuing station. An OTC assembling process provides an ID document “on-the-spot”. (An illustrative example of an OTC assembling process is a Department of Motor Vehicles (“DMV”) setting where a driver's license is issued to person, on the spot, after a successful exam.). In some instances, the very nature of the OTC assembling process results in small, sometimes compact, printing and card assemblers for printing the ID document. It will be appreciated that an OTC card issuing process can be by its nature an intermittent—in comparison to a continuous—process.
OTC identification documents of the types mentioned above can take a number of forms, depending on cost and desired features. Some OTC ID documents comprise highly plasticized poly(vinyl chloride) or have a composite structure with polyester laminated to 0.5-2.0 mil (13-51.mu.m) poly(vinyl chloride) film, which provides a suitable receiving layer for heat transferable dyes which form a photographic image, together with any variant or invariant data required for the identification of the bearer. These data are subsequently protected to varying degrees by clear, thin (0.125-0.250 mil, 3-6.mu.m) overlay patches applied at the printhead, holographic hot stamp foils (0.125-0.250 mil 3-6.mu.m), or a clear polyester laminate (0.5-10 mil, 13-254.mu.m) supporting common security features. These last two types of protective foil or laminate sometimes are applied at a laminating station separate from the printhead. The choice of laminate dictates the degree of durability and security imparted to the system in protecting the image and other data.
UV Security Features in ID Documents
One response to the problem of counterfeiting ID documents has involved the integration of verification features that are difficult to copy by hand or by machine, or which are manufactured using secure and/or difficult to obtain materials. One such verification feature is the use in the card of a signature of the card's issuer or bearer. Other verification features have involved, for example, the use of watermarks, biometric information, microprinting, covert materials or media (e.g., ultraviolet (UV) inks, infrared (IR) inks, fluorescent materials, phosphorescent materials), optically varying images, fine line details, validation patterns or marking, and polarizing stripes. These verification features are integrated into an identification card in various ways and they may be visible or invisible (covert) in the finished card. If invisible, they can be detected by viewing the feature under conditions which render it visible. At least some of the verification features discussed above have been employed to help prevent and/or discourage counterfeiting.
Covert security features are those features whose presence is not visible to the user without the use of special tools (e.g., UV or IR lights, digital watermark readers) or knowledge. In many instances, a covert security feature is normally invisible to a user. Some technologies that involve invisible features require the use of specialized equipment, such as a detector or a device capable of reading digital watermarks. One type of covert security feature is the printing of information (images, designs, logos, patterns, text, etc.) in a material that is not visible under normal lighting conditions, but can be viewed using a special non-visible light source, such as an ultraviolet (UV) or infrared (IR) light source. Use of UV and/or IR security features can be advantageous because although the devices (for example, UV and/or IR light sources) required to see and use such features are commonly available at a reasonable cost, the ability to manufacture and/or copy at least some implementations of such features is far less common and can be very costly. UV and IR based covert security features thus can help deter counterfeiters because the features cannot be copied by copiers or scanners and are extremely difficult to manufacture without the requisite know-how, equipment, and materials.
For example, the assignee of the present invention has developed and marketed a proprietary product called PolaPrime-UV™ PolaPrime-UV™ is a type of security feature. One application of PolaPrime-UV™ is for full color photo quality printing of fixed (i.e., not variable data) fluorescent images. The artwork that can be printed using PolaPrime-UV™ includes many images that can be produced with a combination of red, green, and blue phosphors. Under the appropriate light (e.g., a light source capable of providing UV light), the effect seen when viewing an image printed with PolaPrime-UV™ is similar in appearance to a television screen in that the image is formed by emission of light rather than reflection as with ink on paper. To date, PolaPrime-UV™ has been a reliable authenticator for genuine identification documents.
Printing of Covert Materials such as UV
Many images, such as color images, are formed by subtractive techniques, e.g., light is passed through absorbing dyes and the combination of dyes produce an image by sequentially subtracting cyan, magenta, and yellow components to provide the full color image. In the case of a UV fluorescing image, the UV image is formed by light emitting from fluorescing dyes or pigments as they are activated by a UV light or energy source. A UV image can be imparted to an ID document via methods such as thermal transfer or D2T2.
Regardless of whether the UV materials are imparted via D2T2 or mass transfer panel, both panels produce transmissive images—the mass transfer panel produces a bitonal (e.g., two tones) image and the dye sublimation panel produces a monochromatic (or shaded) image.
Optically Variable Devices for Identification Documents
Color shifting and other optically variable pigments, inks, dyes, and colorants (collectively “optically variable media”) have a feature of appearing to change color as the viewing angle of an observer changes (or as the angle of incident light striking the media changes). Optically variable media have been used on security documents, such as identification cards, credit cards, checks, title documents, currency, etc. The optically variable property provides several advantages when used on security documents: (a) the presence and appearance of optically variable quality provides another “check” or method to authenticate the security document; (b) optically variable media are generally more difficult for a layman to obtain and use properly, thus helping to prevent (or at least limit) forgery and to make forgeries and/or alteration easier to detect; and (c) photocopiers and scanners generally will not reproduce many types of optically variable media, helping to reduce unauthorized reproduction or counterfeiting of such documents. Optically variable media also can be used with many other different types of articles, such as consumer goods (e.g., toys, cars), paper products (e.g., greeting cards, magazines), and in the fine arts (e.g., works of art).
Several methods exist to create optically variable media and to apply such media to security documents. One method involves dispersing in a medium (e.g., paint or ink) a plurality of relatively small particles (typically flakes) that have specific optical properties. One example of a particle can comprise a plurality of thin film layers, each film having a particular color and/or optical property. Another example of a particle that can have an optically varying appearance is described in a commonly assigned patent application Ser. No. 09/969,200 (Now U.S. Pat. No. 6,827,277), entitled “Use of Pearlescent and Other Pigments to Create Security Documents”, by Bentley Bloomberg and Robert L. Jones, filed Oct. 2, 2001 (hereinafter “the '200 application”), the contents of which are incorporated by reference herein in their entirety. The '200 application describes a media having optically variable properties which includes, in one embodiment, particles comprising flat, irregularly shaped mica platelets coated with titanium dioxide and/or iron oxide. These particles, when dispersed in a media, can give a generally “pearlescent” effect, with smaller particles producing a “satin” effect and larger particles producing a “glitter” effect. In many instances, optically variable media are incorporated into a material such as a laminate layer or overlaminate layer, providing an optically variable indicia that overlays other information on the card. Generally, such an optically variable indicium contains “fixed” data (information that is the same from card to card).
For purposes of identification (e.g., of the bearer of an ID document or of the ID document itself), an ID document can include at least one image that is an “identification quality” likeness of the holder such that someone viewing the card can determine with reasonable confidence whether the holder of the card actually is the person whose image is on the card. “Identification quality” images, in at least one embodiment of the invention, include images that, when viewed using the proper facilitator (e.g., an appropriate light source for certain covert images, an appropriate temperature source for thermachromic images, etc.), provide a discernable image that is usable for identification or authentication purposes. To date, however, it has been very difficult to print images such as driver's license portraits with covert (i.e., not visible to an unaided human eye) materials and/or printing media such as UV, IR, thermachromic (materials whose appearance changes and/or becomes visible to a naked human eye with temperature), ferrofluids (materials whose appearance changes and/or becomes visible to a naked human eye upon application of a magnetic field) materials, where the quality of the covert image is sufficient to enable the image to be relied upon for identification or authentication. This can be especially difficult when attempting to print color images using covert materials.
Further, because of the enhanced security provided by the use of full color UV printing, such as is proposed in co-pending and commonly assigned U.S. patent application Ser. No. 10/330,032 (entitled “Covert Variable Information on Identification Documents and Methods of Making Same” and published as US Pub. 2003-0173406, the contents of which are incorporated herein by reference), it would be advantageous to be able to print variable or personal UV information at the time of card personalization, in one, two, or three UV colors, especially images that have a high enough quality to be used for authentication and/or identification. It also would be advantageous if the same information could be printed in a visible and invisible (e.g., UV) form at substantially the same time or at substantially the same printing step, where the covert image would be “identification quality”.
Although it is known to use optically variable media on security documents, use of such media can sometimes have limitations. For example, many optically variable media are substantially opaque, which can limit both their application and use on particular types of security documents, as well as the type and/or design of indicia that are printable with such optically variable media. For example, for some types of security documents (e.g., drivers licenses, identification cards), the issuer may wish to provide a lot of information in a relatively small card area. Security documents often are printed with information such as images of the bearer of the card. Overlaying optically variable indicia over such bearer images can be difficult, however, because many of the optically variable inks are opaque enough to interfere with the visibility of the original (visible) image being overlaid. The relative opacity of many optically variable media means that an indicium (printed with most optically variable media) that is intended to overlay other information might have to have an “open” type of design (such as a design with widely spaced lines, or significant spaces between lines/dots), to permit information overlaid by the indicia to be substantially perceived.
Thus, applying an optically variable media that is opaque to such a card and printing an image with it means that it can be difficult to put other information in that area that was printed/overlaid using the optically variable and still have the non-optically variable information be perceivable to an unaided human eye (for authentication or other purposes).
Another disadvantage of at least some types of optically variable media is that these media can be difficult to apply as part of card personalization (that is, it is often very difficult to print personalized information on a security document using optically variable media).
In one aspect of the invention, we provide methods by which one improves a digital image from which a covert image is formed. One aspect of our invention provides improvements to reduce a “washed-out” effect that can occur when a covert image that has been printed using a covert media such as UV ink, IR ink, thermachromic ink, inks comprising ferrofluids, and the like, is appropriately stimulated so as to cause the covert image to become visible. For example, such washed out effect can be seen when a UV or IR image fluoresces.
One problem that has prevented covert images such as UV or IR images from being “identification quality” is the problem of blurred image details. For example, a problem that can be associated with printing a UV covert image is that since the UV covert image 14 “glows” under appropriate UV stimulation, image details can be less apparent, blurred or can be completely lost. The UV glowing is capable of essentially “washing out” an image's perceptible crispness (e.g., similar to a situation in which a dimly lighted object is in proximity to a brightly lighted object). Similar problems can exist with IR glowing and with thermachromic inks. The inventors of the instant invention have found that image details can be enhanced to overcome this washout problem. In particular, in at least one embodiment of the invention, the inventors have found that it is possible to digitally process an image prior to printing to compensate for the glowing effect.
UV (and/or IR) image glow which washes out the details of a fluorescing UV (and/or IR) image can thus present a considerable problem in relying upon such covert images for identification. To create a discernable fluorescing image on an ID document (useful for identification and security checks), in accordance with one embodiment of the invention, the inventors have found that we can enhance the digital data that is used to create the UV image. Without the inventive enhancements described herein, for example if one simply prints the digital information as such from a digital camera or scanned image, etc., then one may get (when fluorescing) an image that may not as useful for security or identification purposes due to the washed out effect of the UV image. The details of our inventive techniques follow.
In a further embodiment of the invention, steganographic embedded code, such a digital watermark, can be provided in the covert image 14.
In one embodiment, the invention provides a method of processing a digital image that is to be printed on a surface of an identification document as covert image. At least one of edges and boundaries within the image is detected, the detected edges or boundaries forming an intermediate image. The edges or boundaries within the intermediate image are emphasized.
In one embodiment, the invention provides a method of providing a covert image to an identification document. Contrast is increased in at least a portion of the digital image. The contrast-increased portion of the digital image is dithered. The dithered image is transferred to the identification document.
In one embodiment, the invention provides and identification document comprising a core layer and a cover image printed to the core layer. The core layer comprises a core material capable of having printed thereon an image formed using a covert medium. The cover image is formed by providing a digital image that is to be used as a model to generate the covert image, increasing the contrast in the digital image, detecting edges or boundaries within the digital image, the detected edges or boundaries forming an intermediate image, emphasizing the edges or boundaries within the intermediate image, and printing the emphasized intermediate image in a covert medium on the core layer.
We have discovered ways of using optically variable media and ways of printing it to security documents that can provide advantages over the prior art. In one embodiment, the invention relates to identification and security documents, and in particular, relates to various types of optically variable indicia of personalized data formed on such documents. In one embodiment, the optically variable indicium can have a sheen or luster that can appear to be reflective, mirror-like or iridescent. In at least some embodiments, the optically variable indicium is substantially transparent at a first viewing angle (to permit information overlaid by the optically variable indicium to be perceived at least at the first viewing angle), and the optically variable indicium is able to provide a visible, identification quality indicia at a second viewing angle.
We also provide devices and techniques for being able to print indicia that varies from security document to security document (e.g., printing of variable indicia such as bearer images) using such optically variable indicia. The optically variable indicia can be formed anywhere on the document, and in an advantageous embodiment the optically variable indicia is oriented to or disposed in alignment with another variable indicia, such as a substantially identical non-optically variable indicia of the same personalized data. In one embodiment, the optically variable indicia comprises a variable indicia that overlays (fully or partially) another variable indicia on the card, permitting both indicia to be perceived by an unaided human eye (at different angles of viewing)
In one embodiment, the optically variable indicia is aligned with a variable indicia in a manner permitting the variable indicia to have an appearance that appears to have a sheen or luster or switch from a “positive” image of the indicia to a “negative” image of the indicia, when the identification document is moved from a first viewing angle to a second viewing angle.
For purposes of identification (e.g., of the bearer of an ID document or of the ID document itself), an ID document includes at least one image that is an “identification quality” likeness of the holder such that someone viewing the card can determine with reasonable confidence whether the holder of the card actually is the person whose image is on the card. “Identification quality” images, in at least one embodiment of the invention, include images that, when viewed using the proper facilitator (e.g., an appropriate light source for certain covert images, an appropriate temperature source for thermachromic images, etc.), provide a discernable image that is usable for identification or authentication purposes. To date, however, it has been very difficult to print images such as driver's license portraits with covert (i.e., not visible to an unaided human eye) materials/media such as UV, IR, thermachromic (materials whose appearance changes and/or becomes visible to a naked human eye with temperature), ferrofluids (materials whose appearance changes and/or becomes visible to a naked human eye upon application of a magnetic field) materials, where the quality of the covert image is sufficient to enable the image to be relied upon for identification or authentication. This can be especially difficult when attempting to print color images using covert materials.
In one embodiment, we print the optically variable image of variable data so that it overlays other indicia (fixed or variable) on the identifications document. For example, in an advantageous embodiment we directly align and print an optically variable image of a variable indicium directly over the same non-optically variable indicium that has been printed at that location, so that when the identification document printed in this manner is viewed at a first angle, the variable image of a variable indicium is visible, and when the identification document is viewed at a second angle, the optically variable image becomes visible in the same location. We disclose printing and processing techniques to accomplish this.
In one embodiment, we provide an identification document comprising a document layer and a first indicium. The document layer comprises a material capable of being printed by a thermally transferable optically variable ink. The first indicium is printed on the document layer and comprises personalized data and printed to the document layer by a thermally transferred optically variable ink. The first indicium may be printed to the document layer by disposing a thermally transferable optically variable ink in a mass transfer panel of a printer ribbon adapted for use in a dye diffusion thermal transfer printer, and printing the first indicium as part of a mass transfer printing process. The thermally transferred optically variable ink can be selected and printed such that the first indicium has at least one of a luster, shine, sheen, pearlescent appearance, iridescent appearance, and mirror-like appearance.
The first indicium may comprise a digital image formed by providing an initial digital image that is to be used as a model to generate the optically variable image, the digital image comprising personalized data, increasing the contrast in the digital image, detecting edges or boundaries within the digital image, the detected edges or boundaries forming an intermediate image, and emphasizing the edges or boundaries within the intermediate image.
In one embodiment, the identification document further comprises a second indicium, which can be printed using dye diffusion thermal transfer. The second indicium can be substantially identical to the first indicium, the first and second indicia can be arranged so that at least a portion of one overlays at least a portion of the other.
In one embodiment, the first and second indicia are selected and printed so as to give the appearance of a single image having an appearance that shifts from a positive image to a negative image depending on the angle of viewing.
In one embodiment, we provide a method of printing personalized data to an identification document in an optically variable printing medium. We increase contrast in at least a portion of a digital image, and dither the contrast-increased portion of the digital image. We then thermally transfer the dithered image on an identification document using an optically variable printing medium.
In a further embodiment, we provide a method of printing personalized data to an identification document. We receive a first digitized image, the image comprising personalized data, and a second digitized image that comprises a substantial inverse of the first image. We select a first subset of pixels of the first image as a first printing model and a second subset of pixels of the second image as a second printing model. We print the first printing model to a first location on an identification document using a first printing medium, to a first location on an identification document and print the second printing model to a second location on an identification document using a second printing medium.
The foregoing and other features and advantages of the present invention will be even more readily apparent from the following Detailed Description, which proceeds with reference to the accompanying drawings and the claims.
Of course, the drawings are not necessarily drawn to scale, with emphasis rather being placed upon illustrating the principles of the invention. Relative dimensions of identification documents, laminate layers, indicia, etc., are provided for illustrative purposes only and are not limiting. In addition, in the drawings, like reference numbers indicate like elements or steps. Further, throughout this application, certain indicia, information, identification documents, data, etc., may be shown as having a particular cross sectional shape (e.g., rectangular) but that is provided by way of example and illustration only and is not limiting, nor is the shape intended to represent the actual resultant cross sectional shape that occurs during manufacturing of identification documents.